In the practice of diagnostic medicine, it is often necessary or desirable to perform a biopsy, or to sample selected tissue from a patient for medical evaluation. Cytological and histological studies of the biopsy sample can then be performed as an aid to the diagnosis and treatment of disease. Biopsies can be useful in diagnosing and treating various forms of cancer, as well as other diseases in which a localized area of affected tissue can be identified.
Biopsies are routinely performed on tissue using a needle set, which typically includes a stylet with a pointed tip and a notch defined near its distal end. The stylet is slidably disposed within a cannula so that the notch can be alternately exposed or covered. Such needle sets are used with or incorporated in various forms of biopsy devices, such as single action or double action biopsy devices.
More specifically, one known exemplary single action biopsy device includes a hollow needle. A stylet is slidingly disposed within the hollow needle lumen and is moveable relative to needle. A distal end of the stylet is provided with a tissue cutting-point and a tissue opening is positioned adjacent to the distal end for receiving tissue samples. The stylet is slidable relative to needle between a first or retracted position and a second or extended position.
In the first position, the stylet is retracted within the needle such that the needle covers the tissue opening. In the second position, the distal end of the stylet is extended away from the needle to expose the tissue opening to tissues at the biopsy site.
During a biopsy procedure, the device will be positioned within a cavity at a targeted site for the biopsy. The stylet is momentarily driven into the tissue and tissue then prolapses into the tissue opening. The needle is then advanced along the stylet to cover the tissue opening. This forward movement of needle severs the prolapsed tissue to obtain a tissue sample, which becomes trapped in tissue opening of the stylet. With the needle 22 blocking the opening of tissue opening, the biopsy device is then withdrawn from the target site, carrying the sample within tissue opening. To collect the biopsy sample, the needle is once again retracted to expose tissue opening of the stylet. The procedure may be repeated several times until satisfactory samples have been obtained.
While single and double action biopsy devices are widely used, a basic problem remains in the field of biopsy, which is the need to obtain a sufficient amount of sample tissue. One potential cause of the problem is that as the needle passes over the tissue opening, the needle has a tendency to push the tissue away from the tissue opening. This results in samples that are inferior in quality or too small, which precludes the pathologist from conclusively determining whether disease is present, and if so, to what extent it has progressed. The pathologist must then issue an inconclusive diagnostic report. This causes the physician to recall the patient and attempt another needle biopsy, or in some situations, the patient is scheduled for a more invasive, traumatic and expensive procedure such as an open surgical biopsy.
The challenge has been to consistently obtain sufficient tissue volume and quality tissue cores, regardless of tissue type, to meet the needs of the pathologist so that a conclusive diagnosis can be achieved.